H2/CO2 및 CH4/CO2 분리용 ZIF 활성탄막 개발

학위논문(박사) -- 서울대학교대학원 : 공과대학 에너지시스템공학부, 2022. 8. Eunhyea Chung.In this thesis, the zeolitic imidazolate framework (ZIF) membrane was developed with the incorporation of activated carbon (AC) and aluminosilicate (AS). For the preparation of AC, H3PO4 was used as an activator agent to create an abundant pore structure. The Brunauer-Emmett-Teller (BET) surface area of AC derived from algae was 783.53 m2/g. The X-ray diffraction (XRD) analysis of AS revealed that AS were crystalline in structure. The surface characteristics of the modified membrane were observed by using XRD and scanning electron microscopy (SEM) analysis. The produced membrane exhibited both particle homogeneous distribution and efficient adhesion. Single gas (H2, CH4, and CO2) tests were performed at room temperature and 100°C. The two mixtures of gases, H2/CO2 and CH4/CO2, were tested at room temperature and 100°C. Permeation results from the ZIF membrane revealed the permeation value of H2 and CO2 were 3164.17 and 156.11 (Barrer), respectively, at room temperature. Permeation results from the ZIF-AC-AS membrane revealed the permeation value of CH4 and CO2 were 207.46 and 232.23 (Barrer), respectively, at room temperature. As the temperature rises from room temperature to 100 °C, the permeation values of CH4 and CO2 decreased slightly to 146.89 and 203.58 (Barrer), respectively.이 연구에서 ZIF 분리먹은 활성탄 및 알루미노실리케이트와 통합했다. 제조된 분리막은 메탄가스, 이산화탄소 가스 등의 가스 분리에 사용했다. 활성탄 제조를 위해 H3PO4를 활성화제로 사용하여 풍부한 기공 구조로 만들었다. 조류에서 추출한 활성탄의 BET(Brunauer-Emmett-Teller) 표면적은 783 m2/g이다. 갈조류로부터 제조된 활성탄은 85%의 탄소 함량을 나타냈다. 알루미노실리케이트의 XRD 분석은 알루미노실리케이트가 구조적으로 결정질임을 보여준다. 알루미노실리케이트의 표면적은 943 m2g-1로 측정되었다. 생성된 멤브레인의 SEM 이미지는 알루미노실리케이트의 통합이 계면 공극 형성을 향상시키고 형태의 기공 차단을 개선한다. 활성탄을 첨가하면 활성탄의 높은 표면적 때문에 멤브레인의 표면이 상대적으로 더 다공성인 성질을 나타낸다. ZIF 분리막의 투과 결과는 상온에서 H2와 CO2의 투과값이 각각 3164.17, 156.11 (Barrer)인 것으로 나타났다. ZIF-AC-AS 분리막의 투과 결과는 상온에서 CH4와 CO2의 투과값이 각각 207.46, 232.23 (Barrer) 인 것으로 나타났다. 상온에서 100℃까지 온도가 상승함에 따라 CH4와 CO2의 투과도 값은 각각 146.86 과 203.58 Barrer 로 약간 감소하였다. 따라서, 이 연구는 ZIF 구조에서 활성탄과 알루미노실리케이트가 기체 투과성을 증가시킨다는 것을 보여주었다.Abstract 1 Chapter 1. Introduction 2 1.1 Background 2 1.2 Research objective 21 Chapter 2. Materials and Methods 22 2.1 Synthesis of Alumino-Silicate (AS) and Activated Carbon (AC) from algae 22 2.2 Membrane fabrication 25 2.2.1 Seed synthesis 25 2.2.2 ZIF-8 membrane fabrication and post-treatment 25 2.2.3 Gas permeation test and characterization 29 Chapter 3. Results and Discussion 38 3.1 AC characterization 38 3.1.1 Scanning electron microscopy (SEM) analysis of AC 39 3.1.2 Energy dispersive X-ray (EDX) analysis of AC 45 3.1.3 X-ray Diffraction (XRD) analysis of AC 47 3.1.4 Brunauer-Emmett-Teller (BET) analysis of AC 49 3.1.5 Thermogravimetric (TGA) analysis of AC 51 3.1.6 Fourier transform infrared (FT-IR) spectroscopy of AC 53 3.2 AS characterization 55 3.2.1 XRD analysis of AS 55 3.2.2 SEM analysis of AS 57 3.2.3 BET analysis of AS 59 3.3 Membrane characterization 60 3.3.1 XRD analysis of membrane (ZIF-AC-AS) 60 3.3.2 SEM analysis of membrane (ZIF-AC-AS) 62 3.3.3 EDX analysis of Membrane (ZIF-AC-AS) 67 Chapter 4. Conclusions 78 Appendices 79 References 88 국문 초록……………………………………………………………………………..100박

MFI ZEOLITE MEMBRANES ON CERAMIC HOLLOW FIBERS: SCALABLE FABRICATION PROCESSES AND HYDROCARBON SEPARATION PROPERTIES

MFI zeolite membranes are attractive for the separation of industrially important hydrocarbon gas mixtures such as xylene isomers, butane isomers and natural gas components, based on the differences in the chemical and physical properties. However, zeolite membranes including MFI membranes have been unsuccessful in achieving economic viability for industrial-scale gas separation applications. The large-scale industrial application of zeolite membrane systems can be realized by overcoming the following barriers: firstly, develop scalable and reliable membrane fabrication strategies to produce the high-performance membrane; secondly, reduce the cost and achieve performance intensification of the membrane system by employing hollow fiber modules with high membrane area per unit volume; and thirdly, obtain a thorough understanding of multicomponent separation behavior in zeolite membranes at industrially interesting conditions. In the above context, the overall focus of this thesis is to develop novel, technologically scalable fabrication strategies to make thin and highly selective MFI zeolite membranes and to understand their synthesis-structure-permeation property relations by a combination of experiment and modeling. This thesis has focused on the MFI zeolite type, because of its particularly attractive properties for a wide range of hydrocarbon separations.Ph.D

Synthesis and performance evaluation of nanocomposite ceramic-sodalite membranes for pre-combustion CO2 capture

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Master of Science in Engineering. 9 February, 2017Global climate change and other environmental disasters have been attributed to continuous anthropogenic carbon dioxide (CO2) emission into the atmosphere. Today, researchers are constantly seeking measures to reduce anthropogenic CO2 emission. Traditionally, absorption technology with use of monoethanolamine (MEA) is used for separating / capturing of anthropogenic CO2. However, the use of MEA is associated with numerous shortcomings, including inefficient energy usage, high operating and capital cost, amine degradation, solvent loss and excessive equipment corrosion. Alternatively, zeolite based membrane systems are promising technique that prove handy and useful than the traditional processes (absorption with monoethanolamine). However, zeolitic membranes with zeolite coating on the supports (i.e. thin-film supported zeolite membranes) are susceptible to abrasion and thermal shock at elevated temperatures due to temperature mismatch between the supports and the membranes, making them to lose selectivity at early stages. On the contrary, nanocomposite architecture membranes, synthesized via pore-plugging hydrothermal route, are more thermally stable and membrane defects are controlled. Nanocomposite zeolite (sodalite) membranes have been proposed for gas separations, most importantly in the separation of H2/CO2, a major component in pre-combustion carbon capture. In addition, sodalite, a porous crystalline zeolite made up of cubic array of β-cages as primary building block having cage aperture in the range of 0.26 and 0.29 nm, is a potential candidate for the separation/purification of light molecules such as hydrogen which has a cage aperture of 0.27 nm under certain process conditions. In this work, nanocomposite architecture hydroxy sodalite membrane with sodalite crystals embedded within α-alumina tubes were successfully synthesized using the pore-plugging hydrothermal synthesis technique and characterized using techniques such as scanning electron microscopy (SEM) and X-ray diffraction (XRD). The morphology of the synthesized membranes shows that sodalite crystals were indeed grown within the porous structures of the support. Furthermore, Basic Desorption Quality Test (BDQT) and gas separation measurement were conducted to evaluate the quality of the as-synthesized membrane in industrial gas separation applications. The effects of operating variables such as pressure at 1.1 bar, 2.0 bar and 3.0 bar. Also, the effects of temperature were conducted on the nanocomposite membrane at 373 K, 423 K and 473 K. Finally, the gases permeation results were fitted with the well-known Maxwell-Stefan model. Results indicated that, the nanocomposite sodalite / ceramic membrane is a potential candidate for removal of H2 from H2/CO2 mixture. The gas permeation measurement from the one-stage nanocomposite membrane shows that the membrane displayed H2 and CO2 permeance of 3.9 x 10-7 mols-1m-2Pa-1 and 8.4 x 10-8 mols-1m-2Pa-1, respectively. However, the morphology of two-stage nanocomposite membrane shows that the support was more plugged with sodalite crystals and the permeance of H2 and CO2 were 7.4 x 10-8 mol.s-1.m-2.Pa-1 and 1.1 x 10-8 mol.s-1.m-2.Pa-1, respectively. Consequently, the H2/CO2 ideal selectivity for the one-stage nanocomposite membrane improved from 4.6 to 6.5 in the two-stage nanocomposite membrane. In conclusion, the two-stage synthesized membrane shows better improvement. The porous support was well plugged and separation performance was evaluated. However, occluded organic matters present in the cages of hydroxy sodalite could have adverse effect on the gas permeation performance of the membrane. It is expected that an organic-free sodalite supported membrane (such as silica sodalite supported membrane) could out-perform the hydroxy sodalite supported membrane reported in this work in term of membrane flux because there will be enough pore space for gas permeation.MT201

Membrane Separation Technology in Carbon Capture

This chapter introduces the basics of membrane technology and the application of membrane separation in carbon capture processes. A number of membranes applicable in pre-combustion, post-combustion or oxy-fuel combustion have been discussed. An economic comparison between conventional amine-based absorption and membrane separation demonstrates the great potential in membrane technology

Zeolite membranes for the separation of krypton and xenon from spent nuclear fuel reprocessing off-gas

The goal of this research was to identify and fabricate zeolitic membranes that can separate radioisotope krypton-85 (half-life 10.72 years) and xenon gas released during spent nuclear fuel reprocessing. In spent nuclear fuel reprocessing, fissionable plutonium and uranium are recovered from spent nuclear fuel and recycled. During the process, krypton-85 and xenon are released from the spent nuclear fuel as process off-gas. The off-gas also contains NO, NO2, 129I, 85Kr, 14CO2, tritium (as 3H2O), and air and is usually vented to the atmosphere as waste without removing many of the radioactive components, such as 85Kr. Currently, the US does not reprocess spent nuclear fuel. However, as a member of the International Framework for Nuclear Energy Cooperation (IFNEC, formerly the Global Nuclear Energy Partnership), the United States has partnered with the international nuclear community to develop a “closed” nuclear fuel cycle that efficiently recycles all used nuclear fuel and safely disposes all radioactive waste byproducts. This research supports this initiative through the development of zeolitic membranes that can separate 85Kr from nuclear reprocessing off-gas for capture and long-term storage as nuclear waste. The implementation of an 85Kr/Xe separation step in the nuclear fuel cycle yields two main advantages. The primary advantage is reducing the volume of 85Kr contaminated gas that must be stored as radioactive waste. A secondary advantage is possible revenue generated from the sale of purified Xe. This research proposed to use a zeolitic membrane-based separation because of their molecular sieving properties, resistance to radiation degradation, and lower energy requirements compared to distillation-based separations. Currently, the only commercial process used to separate Kr and Xe is cryogenic distillation. However, cryogenic distillation is very energy intensive because the boiling points of Kr and Xe are -153 °C and -108 °C, respectively. The 85Kr/Xe separation step was envisioned to run as a continuous cross-flow filtration process (at room temperature using a transmembrane pressure of about 1 bar) with a zeolite membrane separating krypton-85 into the filtrate stream and concentrating xenon into the retentate stream. To measure process feasibility, zeolite membranes were synthesized on porous α-alumina support discs and permeation tested in dead-end filtration mode to measure single-gas permeance and selectivity of CO2, CH4, N2, H2, He, Ar, Xe, Kr, and SF6. Since the kinetic diameter of krypton is 3.6 Å and xenon is 3.96 Å, zeolites SAPO-34 (pore size 3.8 Å) and DDR (pore size 3.6 Å) were studied because their pore sizes are between or equal to the kinetic diameters of krypton and xenon; therefore, Kr and Xe could be separated by size-exclusion. Also, zeolite MFI (average pore size 5.5 Å) permeance and selectivity were evaluated to produce a baseline for comparison, and amorphous carbon membranes (pore size < 5 Å) were evaluated for Kr/Xe separation as well. After permeation testing, MFI, DDR, and amorphous carbon membranes did not separate Kr and Xe with high selectivity and high Kr permeance. However, SAPO-34 zeolite membranes were able to separate Kr and Xe with an average Kr/Xe ideal selectivity of 11.8 and an average Kr permeance of 19.4 GPU at ambient temperature and a 1 atm feed pressure. Also, an analysis of the SAPO-34 membrane defect permeance determined that the average Kr/Xe selectivity decreased by 53% at room temperature due to unselective defect permeance by Knudsen diffusion. However, sealing the membrane defects with polydimethylsiloxane increased Kr/Xe selectivity by 32.8% to 16.2 and retained a high Kr membrane permeance of 10.2 GPU at ambient temperature. Overall, this research has shown that high quality SAPO-34 membranes can be consistently fabricated to achieve a Kr/Xe ideal selectivity >10 and Kr permeance >10 GPU at ambient temperature and 1 atm feed pressure. Furthermore, a scale-up analysis based on the experimental results determined that a cross-flow SAPO-34 membrane with a Kr/Xe selectivity of 11.8 and an area of 4.2 m2 would recover 99.5% of the Kr from a 1 L/min feed stream containing 0.09% Kr and 0.91% Xe at ambient temperature and 1 atm feed pressure. Also, the membrane would produce a retentate stream containing 99.9% Xe. Based on the SAPO-34 membrane analysis results, further research is warranted to develop SAPO-34 membranes for separating 85Kr and Xe.M.S

Helium separation using membrane technology: Recent advances and perspectives

Helium is an unrenewable noble gas produced from natural gas with a wide range of scientific, medical, and industrial applications. Due to the large differences in the kinetic diameters between helium (0.26 nm) and nitrogen (0.364 nm) or methane (0.38 nm), membrane technology has been considered a promising alternative to traditional technologies for helium recovery and purification. This paper systematically reviews the advances in membrane material development for helium separation in recent years. Gas permeation data presented in this work were collected from over 1000 membrane materials, including polymeric, inorganic, and mixed matrix membranes. Moreover, membrane processes for helium recovery and purification from natural gas were critically analyzed and discussed concerning technical feasibility, energy consumption, and separation costs. Challenges in helium purification using membrane technology were also discussed, and potential solutions have been suggested. Lastly, future perspectives on research directions on membrane material development and hybrid helium purification process design and optimization are proposed.acceptedVersio

Synthesis And Characterization Of Zeolite Membranes For Binary Gas Separation [QE391.Z5 T161 2007 f rb].

Tiga jenis membran zeolit MFI (ZSM-5 dan Silicalite-1) dengan kecacatan minimum telah disintesiskan dengan menggunakan cara yang berlainan. Membran tersebut adalah Silicalite-1 (Si/Al = ∞), Na-ZSM-5 (Si/Al = 25) and B-ZSM-5 (Si/B = 100). Three types of MFI zeolite membranes (ZSM-5 and Silicalite-1) with minimum defect were synthesized using different synthesis approach. These membranes were Silicalite-1 (Si/Al = ∞), Na-ZSM-5 (Si/Al = 25) and B-ZSM-5 (Si/B = 100)

Review on Carbon Capture in ICE Driven Transport

The transport sector powered by internal combustion engines (ICE) requires novel approaches to achieve near-zero CO2 emissions. In this direction, using CO2 capture and storage (CCS) systems onboard could be a good option. However, CO2 capture in mobile sources is currently challenging due to the operational and space requirements to install a CCS system onboard. This paper presents a systematic review of the CO2 capture in ICE driven transport to know the methods, techniques, and results of the different studies published so far. Subsequently, a case study of a CCS system working in an ICE is presented, where the energy and space needs are evaluated. The review reveals that the most suitable technique for CO2 capture is temperature swing adsorption (TSA). Moreover, the sorbents with better properties for this task are PPN-6-CH2-DETA and MOF-74-Mg. Finally, it shows that it is necessary to supply the energy demand of the CCS system and the option is to take advantage of the waste heat in the flue gas. The case study shows that it is possible to have a carbon capture rate above 68% without affecting engine performance. It was also found that the total volume required by the CCS system and fuel tank is 3.75 times smaller than buses operating with hydrogen fuel cells. According to the review and the case study, it is possible to run a CCS system in the maritime sector and road freight transport